It is well-known in the art to house laboratory animals, such as mice and rats, in cages. It is also well-known in the art to house the cages on racks. These cages are typically ventilated and, when placed in a rack, environmentally controlled (e.g., air-flow and air-exchange rate) by a fan system of the rack. In general, the rack fan system provides air under pressure to each of the cages within the rack, and exhausts air from the cages and the rack, as is known in the art.
While prior art ventilated cage and rack systems have been satisfactory, the air within the cage must be changed, or refreshed, on a periodic basis to prevent ammonia build-up, humidity build-up, carbon monoxide build-up, or the build-up of other potentially harmful gases, which may have an adverse effect on the animal within the cage. Changes in temperature in the cage and rack system must also be monitored and controlled to protect the animals housed in the cages. Although the prior art ventilated cage and rack systems did put the cages under positive pressure to create air flow through the cage, those systems do not have the capability to monitor and maintain the desired air flow within the cage and rack or to otherwise monitor and control the environment in the cage and rack. Typically, the supply air system is set for a predetermined air flow rate into the rack, and the exhaust air system is set at a maximum air flow rate. Such a configuration does not adjust air flow into and out of the system as the input and exhaust filters clog, which always occurs. Thus, current rack and cage ventilation systems cannot provide rack and/or cage-level control of the environment in the rack and/or cages. There thus exists a need in the art for a system for monitoring and controlling the air flow within the rack and to the cage at both the rack level and cage level.